package exer;

/**
 * @author shkstart
 * @create 2022-08-15-15:01
 */
public class jian25 {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {


        if(l1==null){
            return l2;
        }
        if(l2==null){
            return l1;
        }

        ListNode dummyHead = new ListNode(-1);
        ListNode last = dummyHead;
        while (l1 != null && l2 != null) {
            if (l1.val <= l2.val) {
                last.next = l1;
                last = l1;
                l1 = l1.next;
            }else{
                last.next = l2;
                last = l2;
                l2=l2.next;
            }
        }
        if (l1 == null) {
            last.next = l2;
        }
        if (l2 == null) {
            last.next = l1;
        }
        return dummyHead.next;
    }

}
